Apparatus and method for deployment of a therapeutic device using a catheter

ABSTRACT

The apparatus for deployment of an intravascular therapeutic device, includes an elongated, flexible pusher member and a therapeutic device connected to a severable portion of a first connector member mounted to the flexible pusher member with an elongated second connector member connected to the therapeutic device. The first connector member or second connector member may be capable of being broken by heat, and a heat source is provided for heating and breaking the first connector member or the second connector member to release the therapeutic device.

CROSS REFERENCES TO RELATED APPLICATIONS

This is a continuation of application Ser. No. 12/814,397 filed 11 Jun.2010, now U.S. Pat. No. 8,298,256, which is a continuation ofapplication Ser. No. 11/726,074 filed 21 Mar. 2007, now U.S. Pat. No.7,740,637, which is a continuation-in-part of application Ser. No.11/020,936, filed 22 Dec. 2004, now U.S. Pat. No. 7,198,613, which is acontinuation of application Ser. No. 10/290,777, filed 7 Nov. 2002, nowU.S. Pat. No. 6,966,892, which is a continuation of application Ser. No.09/501,466, filed 9 Feb. 2000, now U.S. Pat. No. 6,478,773.

FIELD OF THE INVENTION

This invention relates generally to devices for intravascularinterventional therapeutic treatment or vascular surgery for treatmentof defects in the vasculature, and more particularly concerns a systemand method for delivering intravascular interventional devices, such asfor treatment of aneurysms.

BACKGROUND OF THE INVENTION

Vascular interventional devices such as vasoocclusive devices aretypically placed within the vasculature of the human body by use of acatheter. Vascular interventional devices such as stents can be placedwithin an occluded vessel to facilitate blood flow through the vessel,and vasoocclusive devices are typically either placed within a bloodvessel to block the flow of blood through the vessel by forming anembolus, or are placed within an aneurysm stemming from the vessel toform an embolus within the aneurysm. Stents can have a wide variety ofconfigurations, but generally need to be placed and then released at adesired location within a blood vessel. Vasoocclusive devices used forthese procedures can also have a wide variety of configurations, andaneurysms have been treated with external surgically placed clips,detachable vasoocclusive balloons and embolus generating vasoocclusivedevices such as one or more vasoocclusive coils.

The delivery of such vasoocclusive devices have typically beenaccomplished by a variety of means, including via a catheter in whichthe device is pushed through an opening at the distal end of thecatheter by a pusher to deploy the device. The vasoocclusive devices canbe produced in such a way that they will pass through the lumen of acatheter in a linear shape and take on a complex shape as originallyformed after being deployed into the area to be treated, such as ananeurysm.

One conventional releasable balloon catheter used to embolize vascularlesions has a tube portion made of a material such as a hydrophilicpolymer, located between the catheter and the balloon, that can bemelted by heating the tube, or can be dissolved in the blood whenheated, and electrodes are provided for heating the tube. Anotherconventional technique for separating a balloon from a balloon catheterinvolves the melting and breaking of a connecting member between theballoon and the catheter body, when power is supplied to electrodesprovided for heating the connecting member. When the connecting memberis heated to temperatures of about 70° C. and slight tension is applied,the balloon can be separated from the main catheter body.

An implant delivery assembly is also known that is used for delivery ofimplants such as embolic coils, utilizing a shape memory decouplingmechanism activated when exposed to body temperature. A cooling solutionis flushed through the catheter during introduction and placement of theimplant in order to prevent premature release of the implant prior tothe time that the implant is to be released. Another implant deliveryassembly includes an electrical heating system for heating the couplingmechanism to a temperature at which the shape memory material returns toits original shape, to deploy the implant.

Another device is known in which a device to be implanted is detached byapplication of a high-frequency current which melts and severs a resinthat is used to retain the device to be implanted until the device is tobe deployed. In another known device, an electrolytically severable linkis dissolved by activation of a power source electrically coupled to theelectrolytically severable link to detach the device to be implanted.

In another conventional technique, a conductive guidewire delivers ahigh frequency current through the guidewire to melt and sever a jointto detach an implanted device from the guidewire. The patient isgrounded during the procedure, and current is introduced via theguidewire, rather than with a two way current path.

Such devices that release the interventional device by melting ordissolving the intermediate section between the catheter tip andimplanted device may cause thermal damage of surrounding tissues duringdetachment that can cause embolization in the bloodstream, and may alsopotentially release undesirable particles of materials into thebloodstream that can also cause embolization in the bloodstream. Thereis therefore a need for a precise method of deploying therapeuticinterventional devices without compromising the position of the implant,without causing thermal damage to surrounding tissues, and withoutreleasing undesirable particles of materials into the bloodstream andrisking the formation of emboli in the bloodstream. The presentinvention meets these and other needs.

SUMMARY OF THE INVENTION

Briefly, and in general terms, the present invention provides for anapparatus for deployment of an intravascular therapeutic device, such asa vasoocclusive device, a microcoil, at least one electrode, a stent, ora coated coil, for example, using an elongated, flexible pusher member.The therapeutic device is connected to a first connector member mountedto the flexible pusher member with an elongated second connector memberconnected between the first connector member and the therapeutic device.At least one of the first and second connector members includes aseverable portion that is capable of being severed, such as by meltingor degradation, by heat. A heat source is provided for heating andbreaking the severable portion of the first or second connector memberto release the therapeutic device. The first connector member may beformed from a molded thermoplastic material, such as high densitypolyethylene, and the elongated second connector member may be aconnector fiber, or a ribbon, for example. The elongated secondconnector member may also be formed from a thermoplastic material, suchas high density polyethylene. The heat source is advantageouslycontained substantially within the pusher member, which provides asufficient amount of thermal insulation to eliminate the potential forthermal damage to surrounding tissues during detachment of thetherapeutic device. Since the severable first connecting member isheated and broken at a location fully contained within the pushermember, the potential for releasing undesirable particles of materialsinto the bloodstream and consequent embolization in the bloodstream isvirtually eliminated.

The invention accordingly provides for an apparatus for release anddeployment of a therapeutic device within the vasculature of a patient,the apparatus including an elongated, flexible pusher member having aninterior lumen, a first connector member mounted to the elongated,flexible pusher member. In one aspect, the first connector member mayhave a severable portion capable of being broken by heating disposedwithin the elongated, flexible pusher member. An elongated secondconnector member is connected to the therapeutic device and detachablyconnected to the first connector member. The elongated second connectormember thereby connects the therapeutic device to the pusher member forplacement of the therapeutic device within the vasculature, and in oneaspect, the elongated second connector member may have a severableportion capable of being broken by heating disposed within theelongated, flexible pusher member.

In one aspect, a heat source may be disposed in the interior lumen ofthe pusher member adjacent to the first connector member for heating theseverable portion of the first connector member to cause the severableportion of the first connector member to break and release the elongatedsecond connector member for detaching and deploying the therapeuticdevice from the flexible pusher member when a desired placement of thetherapeutic device within the vasculature is achieved.

In another aspect, the first connector member may be formed from amolded thermoplastic, such as high density polyethylene, for example.The first connector member may be molded in the form of a rod extendingacross the interior diameter of the interior lumen of the pusher member,a post, a ring, or other similar suitable configurations. In anotheraspect, the heat source may include an electrical resistance heat sourcecoil. Alternatively, the heat source may include an induction ring, andmay be included in the first connector member, for severing theelongated second connector member. A control unit is typically connectedto the heat source to supply electrical current to the heat source. Theflexible pusher member typically includes a heat insulating shaft havingan entry port communicating with the interior lumen of the pushermember, and the heat source is disposed in the interior lumen of thepusher member adjacent to the entry port. The flexible pusher member hasa distal tip, and in one aspect, the heat source may be spaced apartfrom the distal tip of the flexible pusher member.

In other aspects, the elongated second connector member may be aconnector fiber, or may be a ribbon. The therapeutic device may be avasoocclusive device, a microcoil, at least one electrode, a stent, or acoated coil, for example.

These and other aspects and advantages of the invention will becomeapparent from the following detailed description and the accompanyingdrawings, which illustrate by way of example the features of theinvention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a top sectional view of a first embodiment of the apparatusfor release and deployment of a therapeutic device.

FIG. 2 is a side sectional view of the apparatus of FIG. 1.

FIG. 3 is a top sectional view of a second embodiment of the apparatusfor release and deployment of a therapeutic device.

FIG. 4 is a top sectional view of a third embodiment of the apparatusfor release and deployment of a therapeutic device.

FIG. 5 is a side sectional view of the apparatus of FIG. 1, illustratingrelease of the therapeutic device.

FIG. 6 is a side sectional view of the apparatus of FIG. 3, illustratingrelease of the therapeutic device.

FIG. 7 is a side sectional view of the apparatus of FIG. 4, illustratingrelease of the therapeutic device.

FIG. 8 is a top sectional view of a fourth embodiment of the apparatusfor release and deployment of a therapeutic device.

FIG. 9 is a side sectional view of the apparatus of FIG. 8.

FIG. 10 is a side sectional view of the apparatus of FIG. 8,illustrating release of the therapeutic device.

DETAILED DESCRIPTION OF THE INVENTION

While vasoocclusive devices have conventionally been delivered to aportion of a patient's vasculature to be treated through a deliverycatheter by means of a pusher device, such conventional methods caninvolve separation of the vasoocclusive device from the pusher device inways that result in injury to the vasculature, such as by causingthermal damage of surrounding tissues during detachment that can causeembolization in the bloodstream, or by release of undesirable particlesof materials into the bloodstream that can cause embolization in thebloodstream.

With reference to FIGS. 1-10, the invention provides for an apparatus 40including an elongated, flexible pusher member 42 for release anddeployment of a therapeutic device 44 such as a vasoocclusive device,which may for example be a microcoil, only a portion of which is shown,within the vasculature of a patient, through a delivery catheter 46. Thetherapeutic device may alternatively be one or more electrodes, a stent,a coated coil, or the like, for example. The pusher member has a shaft47 that provides a measure of thermal insulation to an interior lumen48, as will be further explained below. The shaft of the pusher membertypically has an outer diameter of approximately 0.015″, and an insidediameter of approximately 0.007, and can be formed from polyethyleneterephthalate (PET) tubing.

In a first embodiment illustrated in FIGS. 1, 2 and 5, the pusher memberhas a portion 50 with an entry port 52 in communication with theinterior lumen, and a plug 54 at the distal end 56 of the pusher member,typically secured within the distal end of the pusher member byadhesive, such as a cyanoacrylate adhesive, for example.

A first connector member 58 is mounted to the elongated, flexible pushermember, and has a severable portion 60 disposed within the elongated,flexible pusher member that is capable of being broken by heating. Thefirst connector member is typically formed from a molded thermoplasticmaterial, such as high density polyethylene. In the first embodiment,the first connector member may be molded in the form of a rod 61extending across and connected between opposing sides of the interiordiameter of the interior lumen of the pusher member, as is shown inFIGS. 1 and 2.

In a second embodiment illustrated in FIGS. 3 and 6, in which the sameelements from the first embodiment are shown with the same referencenumbers, the first connector member may have the configuration of a post62 connected at one end to the pusher member and having a free end withan enlarged portion 63 larger than the entry port, and having aseverable portion 64 that is capable of being broken by heating,typically formed from a molded thermoplastic material, such as highdensity polyethylene, as is shown in FIG. 3.

In a third embodiment illustrated in FIGS. 4 and 7, in which the sameelements from the first embodiment are shown with the same referencenumbers, the first connector member may have the configuration of a ring65 connected to the pusher member and having a severable portion 67,that is capable of being broken by heating, typically formed from amolded thermoplastic material, such as high density polyethylene, as isshown in FIG. 4, for example.

In each embodiment, the therapeutic device includes an elongated secondconnector member 66 connected to the therapeutic device, such as bybeing looped through an end coil 68 of a microcoil therapeutic device,for example. The elongated second connector member may alternatively betied or bonded to the therapeutic device, such as by heat bonding, or byan adhesive such as a cyanoacrylate adhesive, for example. The elongatedsecond connector member is typically looped around the first connectormember when the first connector member is a rod or post, or through thefirst connector member, when the first connector member is a ring. Theelongated second connector member may be a connector fiber, or a ribbon,that may be made of polyethylene, or another suitable fiber material,for example. In a presently preferred embodiment, the elongated secondconnector member is formed of polyethylene, and is typically about 0.015to 0.030 inches in diameter, although the elongated second connectormember can be as thin as about 0.0005 inches in diameter, and can beformed from a variety of thermoplastic materials with high tensilestrength. The elongated second connector member may also optionally beformed of a suitable high tensile strength material, for example.

In the foregoing embodiments, a heat source such as a resistive heatsource coil 70 is disposed in the interior lumen of the pusher memberadjacent to the severable portion of the first connector member forheating the severable portion of the first connector member to cause theseverable portion of the first connector member to break and release theelongated second connector member, to thereby detach and deploy thetherapeutic device from the flexible pusher member when a desiredplacement of the therapeutic device within the vasculature is achieved.The heat source may be spaced apart from the distal end of the pushermember. The heat source is connected by electrical connectors 72 to acontrol unit 74 which supplies electrical current to the resistive heatsource coil to cause the severable connector member to break and releasethe therapeutic device. Alternatively, the heat source may deliver heatto the severable connector member by other means, such asthermo-mechanical, electromagnetic or RF energy, for example. The lumenof the pusher member advantageously provides an insulative space andwall thickness to contain the heating of the severable connector memberto avoid thermal damage to surrounding tissues, and to help containpieces of the severable connector member that may be formed duringheating of the severable connector member to deploy the therapeuticdevice. The therapeutic device is thus detachably connected to the firstconnector member by the elongated second connector member, for placementof the therapeutic device within the vasculature.

In a fourth embodiment illustrated in FIGS. 8-10, in which the sameelements from the first embodiment are shown with the same referencenumbers, the first connector member has the form of a ring 76 mounted tothe elongated, flexible pusher member. In the fourth embodiment, thefirst connector member is preferably an induction ring providing a heatsource disposed in the interior lumen of the pusher member, and having anarrow, thin edge portion or blade 78, that can be heated. The blade ispositioned to be in contact with the elongated second connector member66, such as a fiber or ribbon that will melt when heated sufficiently,as explained above. The second connector member is connected to thetherapeutic device, so that when the blade of the induction ring isheated, such as by electrical current from electrical connectors 72connected to a control unit 74, as explained above, the first connectormember will sever the second connector member, to release thetherapeutic device.

It will be apparent from the foregoing that while particular forms ofthe invention have been illustrated and described, various modificationscan be made without departing from the spirit and scope of theinvention. Accordingly, it is not intended that the invention belimited, except as by the appended claims.

What is claimed is:
 1. An apparatus for release and deployment of atherapeutic device within the vasculature of a patient, comprising: anelongated, flexible pusher member having an interior lumen; a firstconnector member mounted to said elongated, flexible pusher member, saidfirst connector member including an induction ring disposed in theinterior lumen of the pusher member, said induction ring having an edgeportion configured to be heated; an elongated second connector memberconnected to a therapeutic device and detachably connected to the firstconnector member, said elongated second connector member therebyconnecting the therapeutic device to the pusher member for placement ofthe therapeutic device within the vasculature, said second connectormember having a severable portion configured to be broken by heatingdisposed within said elongated, flexible pusher member, said severableportion of said second connector member being positioned in contact withsaid edge portion of said induction ring for heating said severableportion of said second connector member to cause said severable portionof said second connector member to break and release the elongatedsecond connector member for detaching and deploying the therapeuticdevice from the flexible pusher member when a desired placement of thetherapeutic device within the vasculature is achieved.
 2. The apparatusof claim 1, further comprising a control unit, and wherein saidinduction ring is connected by electrical connectors to the control unitwhich supplies electrical current to the induction ring.
 3. Theapparatus of claim 1, wherein said flexible pusher member comprises aheat insulating shaft.
 4. The apparatus of claim 1, wherein said pushermember includes an entry port communicating with said interior lumen ofsaid pusher member, and said induction ring is disposed in the interiorlumen of the pusher member adjacent to said entry port.
 5. The apparatusof claim 1, wherein said elongated second connector member is aconnector fiber.
 6. The apparatus of claim 1, wherein said elongatedsecond connector member comprises a ribbon.
 7. The apparatus of claim 1,wherein said flexible pusher member has a distal tip, and the inductionring is spaced apart from said distal tip of said flexible pushermember.
 8. The apparatus of claim 1, wherein said therapeutic device isa vasoocclusive device.
 9. The apparatus of claim 1, wherein saidtherapeutic device comprises a microcoil.